Ester-Based Lubricating Oil Composition for EV Cooling and Flash Point

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Solution Overview

Problem

Lubricating oil compositions used in electric vehicles face a trade-off between improving cooling performance and maintaining a high flash point, as reducing viscosity to enhance cooling performance often results in a lower flash point, compromising safety.

Innovation Solution

A lubricating oil composition with a base oil containing 30% to 100% ester-based synthetic oil, specifically selected to have a kinematic viscosity of 2.00 mm2/s to 4.00 mm2/s at 40°C, a specific heat of 1.75 kJ/(kg·K) or less at 20°C, and a density of 0.850 g/cm3 or more, which balances cooling performance and flash point.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the viscosity of lubricating oil composition is reduced to improve cooling performance, then the cooling performance is improved, but the flash point tends to lower

Engineering Contradiction:
Improvecooling performanceVSAvoidflash point
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the kinematic viscosity within 1.50-4.00 mm2/s and specific gravity within 0.820-0.880 to achieve the optimal balance between cooling performance and flash point, resolving the trade-off through quantitative parameter optimization

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by formulating a base oil containing multiple components including ester-based synthetic oils (30-100%), hydrocarbon oils (0-70%), and specific additives, creating a composite lubricating oil composition that simultaneously achieves low viscosity for cooling and high flash point for safety

Inventive Principle:
Principle #40Composite materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The composition achieves superior cooling performance, ensures electrical insulation, and maintains a high flash point, addressing the trade-off between these parameters.

Implementation Method 1

the kinematic viscosity at 40° C. is 2.00 mm2/s to 4.00 mm2/s

Methodology Applied
Scientific EffectViscosity:

Implementation Method 2

the specific heat at 20° C. is 1.75 kJ/(kg·K) or less

Methodology Applied
Scientific EffectSpecific heat:

Implementation Method 3

ensures electrical insulation

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Data Source

PatentUS20230265353A1Lubricating oil composition
Publication Date: 2023.08.24 IDEMITSU KOSAN CO LTD

AI summary

A lubricating oil composition may be superior in cooling performance, ensure electrical insulation, and have a high flash point. Such a lubricating oil composition may include a base oil (A) including an ester-based synthetic oil (A1), the content of the ester-based synthetic oil (A1) is 30% by mass to 100% by mass based on the total amount of the base oil (A), the ester-based synthetic oil (A1) is one or more of an ester (A1-1) of a monohydric alcohol and a monobasic acid and an ester (A1-2) of a monohydric alcohol and a polybasic acid, and the base oil (A) satisfies requirements (1) to (3): Requirement (1): the kinematic viscosity at 40° C. is 2.00 mm2/s to 4.00 mm2/s. Requirement (2): the specific heat at 20° C. is 1.75 kJ/(kg·K) or less. Requirement (3): the density at 20° C. is 0.850 g/cm3 or more.